What would happen if...

[goldstar]

Straight answer - nothing. Not sure what you're looking for though. I'd be interested in knowing which portion of the breaker would trip if you had a faulty device attached to the load end.

I don't mean to stray off topic here but I once had a service call to replace a receptacle. I had the homeowner stand at the top of the stairs and tell me when the lights on my plug-in tester went out. I switched each breaker on and off, went through an entire 40 circuit panel and the lights never went off. I then shut one breaker at a time and kept it off until I finally got the lights to go out. Long story short, there were 3 s/p, one inch breakers all surprisingly tied to the same phase that controlled this device. I subsequently found the JB that these were tied into and made the correction. The frightening part of this is that the HO recently had a service upgrade and by pure chance these branch circuits all ended up on the same phase.

My curiosity here again is that if this device had a defect, which breaker would have tripped? Is this the nature of your question ?

 

[Bjenks]

Actually, the way to do that is to feed one conductor at the near end of the string, and feed the other conductor at the far end of the string. In total, three wires are needed for each string, one of which has no fixtures tied to it; it just feeds the far end.

Series lighting is another way to supply a long single run with only two conductors, as long as you can find appropriate bulbs and the right supply voltage. Added: Isn't it amazing how a thread strays off topic?

For landscape lighting and to show that two circuits on the same phase can be tied together without a problem I mentioned the loop method. I also included my detail that I supply to the contractors when they don't understand my requirement. Note that connecting two wires to the same terminal is the same as a tandem breaker and a loop is the same as tying the wires together at the end.

 

[chevyx92]

I have never gotten a straight answer from anyone on this question...

What would happen if you took the two legs from a 1-inch BR "twin" breaker, which are on the same bar within the panel, ran them 25 feet and then touched the two legs together?

You mean in as PROBLEMS? Or go BANG??? NO bangs would happen what so ever!!!! Problems would be code violations but I suspect you're not wondering about that. Two wires from the same phase will never do anything as fars bangs/pows/disasters are concerned.